Signaling system



July 15 1924.

1,501,726 C. W. RICE SIGNALING SYSTEM Filed June 5, 1919 Inventor:Chester W.Rice,

' His .i'" Lt,TT1@S Patented July 15, 1924.

H UNITED STATES 1,501,726 PATENT OFFICE.

CHESTER W. RICE, F SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRICCOMPANY, A CORPORATION OF NEW YORK.

} SIGNAIJNG SYSTEM.

Application filed June 5,

To all whom it may concern:

Be it known that I, CHEs'rER W. RICE, a citizen of the United States,residing at Schenectad in the county of Schenectady,

State of ew York, have invented certain new and useful Improvements inSignaling Systems, of which thefollowing is a specifioation.

. My present invention relates to signaling systems and moreparticularly to a system for receiving signals and producing an audibleindication of the signals received.

The object of my invention is to provide a system for producing anaudible indication by means of signaling currents of inaudiblefrequency, and especially si naling currents of a frequency below audibi'ty.

The novel features which-I believe to be characteristic of my inventionare set forth with particularity in the appended claims, the inventionitself however both as to its organization and method of operation willbest be understood by reference to the following description taken inconnection with the accompanying drawing in which I have indicateddiagrammatically in Figs. 1, 2 and 3 three different ways in which myinvention may be carried into eifect.

My improved system as indicated in the drawing makes use of a Wheatstonebridge having the usual four arms 1, 2, 3 and 4. Arm 1 includes theplate circuit. of an electron discharge relay 5 having a cathode 6, ananode 7 and a grid 8 enclosed in an evacuated envelope. Arm 2, asindicated in Figs. 1 and 3, is made up of a resistance 9 and a condenser10, and arms 3 and {l are made up of resistances 11 and 12 respectively. A source of current 13 ofaudible fre quency is connected to theopposite terminals .14 and 15 of the bridge and a signal indicatingdevice, which in the present case is the usual telephone receiver 16, isconnected to the othertwo opposite terminals 17 and 18. Condensers 19and 20 are preferably inserted in series with the receiver. A source ofdirect current 21 is included in series with the source of audiblefrequency current 13 for the purpose of supplying the normal constantcurrent for the operation of the electron discharge relay 5. Theelectron discharge relay is provided with a grid circuit which includesthe grid 8, a resistance 22 and the cathode 6 of the device. The arms ofthe bridge are so adjusted that under normal 1919. Serial no. 301,987.

conditions a balance is obtained and no current will flow through thereceiver 16. The

signaling-current supplied from the conductors 23 and 24: is then causedto flow throughresistanoe 22 and thus produce a variation in potentialof the grid 8. As a result the resistance of the electron dischargerelay 5 is varied and the balance of the bridge is u set. Current fromthe source Fig. 2, the arm 2 of the bridgeis also made up of an electrondischarge relay 25, the grid 26 of which may if desired be permanentlyconnected to the cathode 27. In some cases the use of a second electrondischarge relay will enable the desired balance of the bridge to beobtained more readily. By varying the potential of the grid by means ofa source of potential 30 the resistance of relay 25 may be varied andthe desired balancing of the bridge obtained. In some cases where thesignaling current is of extremely small intensity the resultantvariation in the balance of the bridge may be too small to produce a"suflicient flow of current thro'ughthe receiver 16 to produce the desired indication. In such case the audible frequency current may becaused to flowthrough. a resistance 28 which is included in the gridcircuit of an electron discharge amplifier 29, the receiver 16 in thiscase being included in the plate circuit of this amplifier. The finalbalancing of the bridge may be effected conveniently by variation ofresistances 30 which are included in the filament heating circuits.

The system which I have described is adapted to a great variety of usesamong which is the reception of continuous wave radio telegraphicsignals which, as is well known, will' produce no audible indication inthe ordinary receiving devices unless they are combined with locallyproduced waves according to the well known heterodyne method or brokenup into groups by the so called ticker method. My invention permits ofthe reception of such signals without recourse to the expedientsmentioned.

While I have indicated three modificaemployed without departing from thescope of my invention as set forth in the appended claims.

What I claim as new and desire to secure it by Letters Patent of theUnited States, is

l. The combination in a signaling system of a source ofsignalingtcurrent of-inaudible frequency, a lVheatstone bridge, a sourceof current of audible frequenc connected to two opposite terminals ofsai bridge, a rec'eiving device connected to the other two oppositeterminals of said bridge, said bridge being normally so adjusted. thatno audible frequency current will flow through said receiving device, anelectron discharge relay in one arm of said bridge and means actuated bythe signaling current for vary-- ing the resistance of said relay andthere-- by causing an audible frequency current to flow in saidreceiving device.

2. The combination in a signaling system of a source of signalingcurrent of inaudible frequency, a l Vheatstone bridge, a source 015current of audible frequency connected to two opposite terminals of saidbridge, a receiving device connected to the other two opposite terminalsof said bridge, said bridge being normally so adjusted that no audiblefrequency current will flow through said receiving device, an electrondischarge relay havin a plate circuit included in one arm of sai bridge,a grid circuit for said relay and means for impressing the signalingcurrent u on said grid circuit.

3. The com ination in a signaling system of a source of signalingcurrent of inaudible frequency, a Wheatstone bridge, a source of currentof audible frequenc connected to two opposite terminals of said bridge,a

receiving device connected to the other two opposite terminals of saidbridge, said brid e being normally so adjusted that no audi le frequencycurrent will flow through said receiving device, two electron dischargerelays in two of the arms of said bridge, and means actuated by thesignaling current for varying the resistance of one of said relays andthereby causing an audible frequency current to flow in said receivingdevice.

a, The combination in a signaling system of a source of signalingcurrent or" inaudible frequency, a Wheatstone bridge, a source ofcurrent of audible frequency connected to two opposite terminals of saidbridge, a receiving device connected to the other two opposite terminalsof said bridge, said bridge being normally so adjusted that no audiblefrequency current will flow through said receiving device, two electrondischarge relays having plate circuits included in two of the arms ofsaid bridge, a grid circuit for one of said. relays and means forimpressing the signaling current upon said grid circuit.

5. Apparatus for amplifying electrical currents comprising a Wh'eatstonebridge having a tri-electrode device connected by its plate and filamentelectrode in one of the branches of the bridge, with the circuitcarrying the current to be amplified connected between the grid andfilament, and an indicator connected across said bridge.

6. Apparatus for. am lifying electrical currents comprising a eatIstonebridge having two t-ri-electrode devices connected by their plate andfilament electrodes in two of the branches of the bridge with thecircuit carrying the current to be amplified connected between the ridand filament of one of said devices an an indicator connected acrosssaid bridge.

in witness whereof, I have hereunto set my hand this 23rd da of May,1919.

CH ESTER W. RICE.

